Support element for underground underworkings

ABSTRACT

A support element for underground underworkings has a sleeve of a flexible fabric permeable to water and air. A central column having a T-shaped vertical cross-section, comprised of a column shaft and a disk-shaped column head, is arranged in the sleeve and made of a hydraulically binding and expandable material introduced under pressure into the sleeve and solidifying in the sleeve to form the central column. A jacket surrounds the column shaft and consists of stacked, empty, fire-retardant automobile tires having openings allowing water, contained in the hydraulically binding and expandable material, and air to exit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to support elements for use particularly inconnection with mining operations, in particular, for undergroundunderworkings.

[0003] 2. Description of the Related Art

[0004] It is known from U.S. Pat. No. 5,143,484 to fill automobiletires, in particular, used automobile tires, with concrete in a circularring shape and to stack the automobile tires filled with hardenedconcrete as a support element between the footwall and the top wall ofunderground underworkings. Because of the weight of the automobile tiresfilled with concrete, stacking is possible only with great forceexpenditure. Since no precise adjustment of a automobile tire stack tothe respective local distance between the footwall and the top wall ispossible, the spacing between the topmost automobile tire and the topwall must be filled by fillers such as wedges, preferably wooden wedges,requiring complex manual labor. A further property of such a supportelement is that it cannot be braced with a predetermined bracing loadbetween the footwall and the top wall. The lack of the bracing loadhowever favors convergence, even convergence of the footwall.

[0005] Further variants of a support element are known from Germanpatent document DE 37 32 894 A1 and U.S. Pat. No. 4,277,204. The supportelements have a rigid jacket casing which, after hardening, of thefilled-in building material can be removed. The disadvantage of suchsupports resides in that a significant part of the support force isremoved as soon as the jacket casing is removed. A further disadvantageresides in the use of the many metal parts which makes the use ofsupport elements in large numbers very cost-intensive.

[0006] In the documents DE 196 08 940 A1 and DE 297 22 995 A1 furtheralternatives are described. For erecting these supports, empty bags offabric are suspended from the top wall and then filled. In practice, itwas found that a rapid filling of the bags is not possible because theholders of the bags on the top wall will tear off as a result of theweight of the still liquid building material so that the buildingmaterial will then flow into the mine section.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide a supportelement for underground underworkings which are comprised of automobiletires and can be braced with a bracing load between the top wall and thefootwall without additional manual force expenditure.

[0008] In accordance with the present invention, this is achieved inthat the support element has a sleeve of a flexible fabric permeable towater and air; a central column having a T-shaped verticalcross-section, comprised of a column shaft and a disk-shaped columnhead, and comprised of a hydraulically binding and expandable materialintroduced under pressure into the sleeve and solidifying in the sleeveto form the central column; and a jacket surrounding the column shaft,comprised of stacked, empty, fire-retardant automobile tires havingopenings allowing water, contained in the hydraulically binding andexpandable material, and air to exit.

[0009] According to the present invention, such a support elementcomprises a central column which, in vertical cross-section, is T-shapedas well as a jacket surrounding the shaft of the column and comprised ofempty automobile tires. The automobile tires are stacked and in this wayform a jacket in which a vertically extending inner shaft is defined.Into the shaft a sleeve is inserted which has the desired T-shapedconfiguration the column to be formed with rotational symmetry.Subsequently, a hydraulically binding as well as expandable material isfilled under pressure into the sleeve. This can be realized preferablyby means of a pump. The material spreads within the sleeve and, as aresult of the air-permeable and water-permeable flexible fabric of thesleeve, substantially only solid components of the introduced materialremain in the sleeve; the material will expand and harden. As a resultof the T-shaped, rotationally symmetrical sleeve, between the top sideof the jacket and the top wall a disc-shaped column head is formed whichhas a horizontal cross-section that is greater than that of the columnshaft. This column head bridges the distance between the top side of thejacket and the top wall. The outer diameter of the column headsubstantially has the same outer diameter as the jacket. As a result ofthis configuration, between the footwall and the top wall asubstantially cylindrical support element is built which, because of thehydraulically binding and expandable material, can be braced with abracing load.

[0010] The fabric or woven cloth which is employed for the sleeve iscomprised, in particular, of a flexible water-resistant woven material,for example, a glass fiber material or synthetic fiber material. Naturalfibers are also conceivable which are impregnated with agents whichincrease the durability of the fabric.

[0011] The material for forming the central T-shaped column is amixture, in particular, of fly-ash of fossil fuels, lime, aluminumpowder, and water. Such a material cannot be charged electrostatically,is non-combustible, and moreover inexpensive. Expansion of the materialis realized as a result of the reaction of the aluminum powder with thelime. If needed, the strength can be improved by addition of Portlandcement as a stabilizer.

[0012] In regard to the automobile tires, care must be taken that theyare fire-retardant. Automobile tires of the newest generation arefire-retardant as a result of their chemical composition. Tires of oldergenerations can be made fire-retardant before their installation, forexample, by foaming a protective layer thereon or by spraying anadhesive or cohesive emulsion thereon. Also, it is conceivable toprovide a subsequent protection against combustibility on site when thetires are in the mounted state. This can be an individual measure or canbe carried out in the context of the overall building measure, forexample, by blowing thereon residual materials or cut-and-fill material.

[0013] As has been discussed above, the column head is configured suchthat it can take on a support action across a large surface area of thetop wall upon finishing the bracing process. As soon as the filled-inmaterial presses the column head against the top wall, the areas of thecolumn head extending circumferentially about the column shaft arepushed, when filling in more material, from above against the jacket ofautomobile tires in the direction toward the footwall so that theflexible jacket between the footwall and the top wall is tensioned orbraced.

[0014] By means of the features according to the invention, it istherefore possible to provide a support element for the undergroundunderworkings, for example, in mining operations and for tunnelconstruction, for securing the top wall against falling rock andconvergence as well as to protect against footwall convergence. Thebracing of the support element with the bracing load between thefootwall and the top wall results because of the material employed forthe central column in that at least one part of the bracing load ismaintained even over an extended period of time.

[0015] Since the automobile tires have air outlet openings which areprovided particularly in the running surfaces of the automobile tires,when the maximum load of the support element is surpassed causing thehardened column to burst, air can be suddenly released from the jacketso that the energy of the released parts can be relieved into the hollowspaces. At the same time, the hollow spaces can also receive thefragments of the burst material of the column. The miners are notendangered by the bursting parts of the column.

[0016] An improved adjustment of the column, on the one hand, to the topwall and, on the other hand, to the jacket comprised of automobile tiresis achieved according to another embodiment of the invention in thatbetween the disk-shaped column head and the top wall a head plate, inparticular, a head plate which has a closed surface, is provided andbetween the column head and the jacket an circular ring-shaped pressureplate is arranged. The material of the head plate and of the pressureplate can be steel. However, a corresponding plastic material is alsoconceivable. Moreover, it is possible that the head plate is profiled inorder to receive optionally additional construction elements, forexample, rails on the top wall.

[0017] A substantially positive-locking adjustment of the head plate tothe top wall is achieved when the head plate is configured to beflexible to a limited extent.

[0018] According to the features of another embodiment, the column hasno direct contact with the footwall. Instead, the end section of thecolumn shaft facing the footwall is positioned in a receptacle with abottom plate, wherein the receptacle is open in a direction to the topwall. The bottom plate forms in this connection the counter abutment tothe head plate and axially receives the braced flexible jacket ofautomobile tires.

[0019] The invention can be further improved in that the receptacle hasa sleeve-like receiving section for the column shaft with support bottomand a foot section which widens conically in the direction toward thefootwall. The receiving section centers accordingly the lower end of thecolumn shaft facing the footwall such that it partially radiallysurrounds the column shaft. The conical foot section, upon surpassing adefined load, can buckle yieldingly and accordingly forms an additionalsafety part of the support element.

[0020] Advantageously, the receiving section can have at least onetransverse opening. The transverse opening, for example, in the form ofa bore, is expediently provided in the wall of the receiving section.This transverse opening serves for removing excess water of the materialfilled into the sleeve.

[0021] Moreover, the support bottom of the receiving section can beflexible, at least to a certain extent, in order to be able to receive aprestress.

[0022] With respect to a problem-free filling process of the sleeve, itis advantageous to provide the section of the sleeve surrounding thecolumn shaft with a filling conduit having an integrated filling valveand extending the filling conduit through the jacket.

BRIEF DESCRIPTION OF THE DRAWING

[0023] In the drawing, the only FIGURE shows a support element accordingto the invention comprised of a central column and a stack of automobiletires surrounding the central column.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The support element 4 which is braced between the footwall 1 andthe top wall 2 of underground underworkings 3 with a bracing loadcomprises basically a central column 5, which is T-shaped in verticalcross-section and has rotational symmetry, as well as a jacket 7surrounding the shaft 6 of the column and comprised of empty, stackedautomobile tires 8 which are fire-retardant.

[0025] The column 5 is formed of a hydraulically binding as well asexpandable material which is introduced under pressure into a sleeve 9which corresponds to the shape of the desired T-shaped configuration ofthe column 5 to be formed. This sleeve 9 extends, on the one hand,vertically through the stack of automobile tires 8 forming a centralinner shaft 10 and, on the other hand, between the uppermost automobiletire 8 and the top wall 2. The material is introduced via a fillingconduit 11 into the sleeve 9. The filling conduit 11 is arranged in theupper area of the sleeve 9 delimiting the column shaft 6 and extendsradially through an automobile tire 8. A suitable filling valve 12 isintegrated into the filling conduit 11.

[0026] The end section 13 of the column shaft 6 neighboring the footwall1 is positioned in a sleeve-like receiving section 14 which is a unitarypart of the receptacle 15 with bottom plate 16. Between the bottom plate16 and the receiving section 14, a bottom section 17 is provided thatextends conically widening toward the footwall 1. The bottom 18 of thecolumn shaft 6 contacts a support bottom 19 of the receiving section 14.

[0027] Moreover, it is shown that a head plate 21 extends between adisk-shaped column head 20 and the top wall 2 and that a pressure plate22 of an annular ring shape is provided between the column head 20 andthe uppermost automobile tire 8 of the jacket 7. The pressure plate 22surrounds the column shaft 6.

[0028] The sleeve 9 is comprised of a fabric which is flexible andallows passage of air as well as water so that substantially only thesolid components of the material remain within the sleeve 9 when thesleeve is filled with the hydraulically binding and expandable material.Water and air can exit between and through the automobile tires 8. Theautomobile tires 8 are provided with openings 23 to allow water and airto pass through. Moreover, in the wall 24 of the sleeve-like receivingsection 14 at least one opening 25 is provided through which excesswater can also exit during filling of the sleeve 9.

[0029] The materials employed for forming the column can be, aside fromfly-ash cement, other hydraulically binding building materials such asanhydrite, gypsum or ready-mix concrete. For the purpose of volumeexpansion of the multi-component mixtures, in addition topore-generating chemical materials, it is also possible to admixpore-generating converted natural materials such as a resin acids andmaterials such as fatty alcohol diglycol ether sulfate (C₁₂-C₁₄).

[0030] The cohesion of the multi-component mixture is realized bystabilizers. These are organic or inorganic, water-soluble components,such as water glass, glycerin, lime solutions, and, in addition,heavy-metal salts for forming insoluble hydroxides.

[0031] While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

What is claimed is:
 1. A support element for underground underworkings,the support element comprising: a sleeve of a flexible fabric permeableto water and air; a central column having a T-shaped verticalcross-section, comprised of a column shaft and a disk-shaped columnhead, and comprised of a hydraulically binding and expandable materialintroduced under pressure into the sleeve and solidifying in the sleeveto form the central column; and a jacket surrounding the column shaft,comprised of stacked, empty, fire-retardant automobile tires havingopenings allowing water, contained in the hydraulically binding andexpandable material, and air to exit.
 2. Support element according toclaim 1, wherein between the disk-shaped column head and a top wall ofthe underworkings a head plate is provided and between the column headand the jacket a circular ring-shaped pressure plate is arranged.
 3. Thesupport element according to claim 2, wherein the head plate is flexibleat least to a limited extent.
 4. The support element according to claim1, further comprising a receptacle with a bottom plate, wherein thereceptacle is open in the direction toward the top wall, wherein thereceptacle is configured to receive a lower end section of the columnshaft facing the footwall.
 5. The support element according to claim 4,wherein the receptacle has a sleeve-shaped receiving section for the endsection of the column shaft, wherein the receiving section is comprisedof a support bottom and a conical bottom section conically widening inthe direction toward the footwall.
 6. The support element according toclaim 5, wherein the receiving section has at least one opening allowingwater contained in the hydraulically binding and expandable material toexit.
 7. The support element according to claim 5, wherein the supportbottom of the receiving section is flexible at least to a limitedextent.
 8. The support element according to claim 1, wherein a sectionof the sleeve surrounding the column shaft comprises a filling conduithaving an integrated filling valve, wherein the filling conduit extendsthrough the jacket.